Signaling system



June 192 D. M. TAGGART SIGNALING SYSTEM Q U fivven/onv Dawson M 7&944/1 C A? .h w bi 1,539,920 D. M. TAGGART SIGNALING SYSTEM Filed D86. 12, 1922 2 Sheets-Sheet 2 *r-Qig hue/775K Dan/son M 577 W AW.

Patented June 2, 1925.-

UNITED STATES PATENT OFFICE...

DAVJ'SON LI. TAGGAET, OF SEATTLE, WASHINGTON, ASSEGNOR- TO AMERICAN TELE- PHONE AND TELEGRAPH GQI'ZPANY. A CORPORATION OF NEW YORK.

SIGNALING SYSTEM.

Application filed December 12, 1922.

To all 10710122. it may concern:

Be it kn wn that I, Dawson M. EAGGART, residing at Seat... in the county of King and State of lVashington. have invented certain Improvements in Signaling Systems, of which the "following is a specification.

This invention relates to rovements in signaling systems and has particular reterence to a telephone exchange system in which a plurality of subscribers lines terminate before a plurality of operators positions.

Objects of the invention are to connect any one ot a plu 'ality oi pos t ons to a calling line through automatic s itehes and to control line signals for said line in such ianner as to indicate which one of a plurality of switches has been connected to said. line.

Other objects are to operate one of a plurality of line signals located at various operators positions in a characteristic manner and to render the remaining: signals inoperative when one of said operators positions is connected to a calling! line through an automatic switch.

The above and other more clearly from the tollowing detailed lescription when taken in connection with the accompanying drawings which illust e a preferred embodiment of the inventi e idea.

In the drawings, Figure IV is a (liag'r: "nniatic illustration of a switchboard showingthe arrangement of the subscribers lines terminating; at the various operators" positions thereofl and the apparatus associa ed with said positions.

Fig. 2 illustrates the circuit arrangement of one ot the automatic switches employed in connecting: a subscribers line to an operators position.

The general arrangement ot the switchboard. as illustrated in Fig. l, contemplates the division of the switchboard into a number o't sections, each of which includes three operators positions. The subscribers lines terminating at the switchboard are pretcrably divided into groups A, B, and C and the lines of each group appear in multiple before all of the operators positions n the various sections of the switchboard. For each group of lines at each position there appears an automatic switch, such as objects will appear Serial No. 606,514.

switches D, H, and 1. Each s ubscribers line in any particular group has a multiple line lamp appearing at one operators position in each section. Each operators posi t-ion is provided-with equipment such as the keys 12 and 80 and the interrupter 27 which are common to the subscribers lines in the various groups which are multipled at said position.

Briefly the operation of the system may be described as follows:

ld hen a call is initiated on a line in any group the multiple line lamps for said line are lighted at corresponding positions in the various sections of the switchboard. The operators at. the various positions who are not occupied in handling calls depress their listening keys 12 and thereby initiate the operation of switches such as D, H. and I. to hunt for the terminals of the calling line. The first at these switches to engage the terminals of the calling line stops ther on and creates a condition which prevents other switches from coming to rest upon. said terminals.

brought to rest upon the terminals of the calling;- line then controls the connection of an interrupter device peculiar to the particular operators position whose switch has found the calling line, to the line lamp appearing in the section in which. said switch is located and flashes said line lamp in a characteristic manner to indicate which one of the operators in said section is to handle the call. Said switch also controls the connection of said operators headset to the calling subscribei"s' substation so that the operator may immediately converse with the calling, subscriber and While securing the desired number may complete a permanent connection to said calling line through a. multiple jack thereof, lVhen the operator has completed the connection she may 'by the actuation of her listening key 12, disconnect her equipment from the calling; line and initiate the operation of theswicth employed in completing said connection to establish another connecti-on to a line upon which an unanswered call is awaiting attention. It the operator desires to vacate her position after attending to a call, she operates the key which has the effect of dis connecting the switch employed. in estab Due to the depression of the listening key, the switch which is iitl lishing the connection from the calling line and preventing said switch from seizing the terminals of some other linewhich is calling. his believed that the operation of this system will now be fully understood from the following detailed description.

Assuming that a subscriber whose line is located in group C and whose substation is indicated by numeral '1 should initiate a call, the removal of the receiver from its hook at the substation establishes an operating circuit for line relay 2, through the contacts of the cutofl relay 3, and the substa' tion apparatus. lVhen the line relay 2 operates, a circuit is established for energizing the relay 4 at position A in the second section and other similar relays which appear at the corresponding position in each of the other sections of the switchboard said other relays being multipled, as indicated, to the conductor 5 over which the relay 4 is energized. The energization of relay 4 and the other relays similar thereto' causes the lighting of line lamps 6 at the various A positions in the diflerent sections, the circuit conductor 7 to which other lines of group C are multipled, as indicated at 8, and the winding of relay 9 of the rotary switch generally indicated by D (Fig. 1) to grounded battery. The mechanism for controlling switch D is indicated in Fig. 1 at E and this mechanism is multipled as indicated at 10 to mechanisms F and G which are employed for controlling, respectively, switches H and I located at position C in the first section and position B in the second section of the switchboard respectively. The relay 4 is utilized to control the operation of three switches located at operators positions which may be in different sections of the switchboard as shown in connection with the group of lines C or which may be in. the same section as shown in connection with the group of lines B. With other relays similar to relay 4 in other sections operated due-to the multiple connections to the conductor 5, it will be obvious that the initia tion of a call in group C, or in any of the other groups, will cause all of theswitches similar to switch D serving that particular group to operate in a manner which will now be described specifically in connection with switch D.

I Assuming that all of the switches are idle when the call is initiated from substation 1 and when relay 9 operates over the circuit described therefor, a circuit is established from grounded battery through the inner right-hand contact of relay 9 and pilot lamp 11 located before the operator at position A in the second section to ground. The oper: ation of other relays similar to relay 9 at the other switches will also close their circuits to light the pilot lamps before the operators at the other positions in the various sections and the lighting of these pilot lamps indicates to the operators that a call is awaiting attention. The operators then depress their master listening keys 12 and await the proper signal which indicates which of the operators is to get the call. It will be assumed that the operator at position A of the second section was the first to depress her listening key 12 and the arms of the various switches occupy such positions that the call willbe routed through this position. When the inner right hand contact of relay 9 is closed a circuit is also established extending from grounded battery through said Contact, the right hand winding of test relay 13, and the normal contact of the differentially. wound relay 14 to ground. The test relav 13 energizes in this circuit to establish a self interrupting circuit for the stepping magnet 15 of switch D, which circuit will presently be traced in detail. The opening of the normal contact of relay 9 disconnects battery at the relay 16 from the normal contacts of relays, similar to relay 9, located at the switches succeeding switchD at position A in the second section of the switchboard so as to prevent these succeeding switches from responding to calls in other groups of lines as long as relay 9 of switch D remains energized thus giving lines in group C preference over lines in the other groups appearing at the various positions A.

The circuit for the stepping magnet 15' which controls the stepping of the wipers 17 to 22 inclusive of switch D extends from grounded battery through the winding and contact of magnet 15, the inner left hand contact of relay 9, the outer left hand alternate contact of test relay 13, the wiper 21 and contact engaged thereby and from thence through the right hand normal contacts of relays similar to relay 4 which have not been operated by the initiation of the call at substation 1. This circuit for the stepping magnet 15 is thus maintained until the; wiper 21. of switch D engages the terminal to which the conductor 23 is connected. Inasmuch as relay 4 is now energized, no ground will be connected to conductor 23,'and therefore. when engagement of wiper 21 with the terminal'to which conductor 23 is effected, the operating circuit for stepping magnet 15 is permanently opened and the wipers of switch D come to restupon the terminals individual to. the

calling subscribers line. This action takes place under the assumption that the wipers of sii'it-ch l.) are the lirst to engage terminals of the calling line. During the operation oi switch l) in hunting for the calling line and while the test relay 13 is operated a tone is connected to the operators telephone indicated at O. T. from the source 24-. through the right hand alternate contact of relay 13. the outer right hand normal contact of relay 25, condenser 26 and from hence to the operators headset. This tone indicates to the operator who has depressed her listening key that the switch is still opcrating and has not stopped upon the terniinals of the calling line.

lVhen the wipers of the switch D engage the terminals of the calling line, relay 13 does not immediately release, due to its original operating circuit being still closed but a circuit is established for relay 25 extending from grounded battery through the contact of relay 16, the outer right hand alternate contact of relay 9, the right hand winding of relay 25, the wiper 22, and terminal engaged thereby, and the outer right hand alternate contact of relay lto ground. Relay 2-5 energizes and in opening its outer right hand normal contact disconnects the apparatus 24: from the operators telephone set and thereby indicates to the operator that switch D has been connected to the "zals and the calling line. lVith the listening lrey 12 depressed at this time, a holding circuit for relay 25 is established extending from ground through the right hand contact of key 12, the left hand winding and inner left hand alternate contact of relay 25 and the winding of relay 16 to grounded battery. Relay 16 energizes in its circuit and thereby disconnects battery through its normal contact from the right hand winding of relay thus breaking the original energizing circuit for the latter re lay. The operation of relay 25 also establishes a circuit for the differential relay 1-1 which circuit may be traced from grounded battery, through the right hand winding ot relay 14:. the outer left hand alternate contact of relay and the left hand contact of the listening ltey 12 to ground. Relay 1%; energizes in this circuit and in opening its normal contact disconnects ground from the right hand winding of test relay 13 thereby permitting this relay to release. The closure of the left hand normal contact of relay 13 connects ground at the outer left hand al ternate contact of relay 9 to the terminal engaged by the wiper 21 so that when the test wipers of other switches similar to switch D engage the terminal corresponding to that now engaged by the wiper 21 the ste ping magnets at said other switches will cont nue to operate and thus prevent the wipers of these switches from coming to rest thereupon. The closure of the inner right hand alternate contact of relay 14L establishes an energizing circuit for cutoff relay 3 of the line 1 and a locliing'circuit for relay 1 1, said circuit being traceable from grounded through the right hand winding and inner right hand alternate contact of relay ll. the outer right hand normal contact of relay 13, the wiper 19 and terminal engaged thereby, and the winding 01" cut cit re ty 0 to ground. The energization of relay 3 in this circuit opens the energizing circuit line relay 2 which thereupon releases and in turn causes the release of relay 1 and other relays similar thereto. lVhen relay 4t releases a circuit is established extending from ground through the conducting segment or" the interrupter 27, the outer right hand alternate contact of relay l l. the inner right hand normal contact of relay 13, the wiper and terminal engaged thereby, the left hand norn'ial contact of relay 4 and the lamp 6 to grounded battery. The lamp 6 now starts flashing under control of the interrupter 27. Inasmuch as the conducting segments of the interrupters at the Various positions are difi erently arranged, as in dicated in Fig. 1, it will be apparent that each operators position will receive a characteristic flashing of the line lamp. Since the wipers of switch D arethe only ones that are now engaged with the terminals of the calling line, it will 'e apparent that the release of all the other relays similar to relay 4; will cause the extinguishment 01 all the line lamps with the exception of the lamp 6 which will now be flashed in its characteristic manner under the control of the interrupter 27 to indicate to the operator at position A in section 2 that her switch is the one engaged with the calling line and that she is to handle the call. She immedi ately releases the listening key 12 and thereby causes the release of relays 16 and 25, the latter remaining); inits released condition due to the tact that the original energizing circuit through its right hand winding is no longer closed since the relay is now released. The closure of the two innermost right hand contacts of relay now connects the operators telephone set through these contacts, the two outermost left hand contacts of relay 14, which is. at this time. en ergized, the wipers 17 and 18 and the terminals engaged thereby and from thence yer the line conductors to the calling subscribers substation 1. The operator may now converse with the calling subscriber to ascertain the number desired and at the same time may insert the plug of the cord circuit J into the jack 29 of the calling subscriber preparatory to completing the connection to the called subscriber over said cord circuit. only, a portion of which is shown. it being understood that this cord circuit may be of any desired type Well known in the art.

If at the time that the relay 4 and other similar relays release there are no other calls awaiting attention, theground is removed call, she again depresses the listening key 12 which establishes a circuit extending from ground through the left hand contact of key 12, left hand normal contact of relay 25, the inner left hand contact and left hand differential winding of relay 14 to grounded battery. The closure of this circuit causes the release of relay 14 and consequent disconnection of the interrupter 27 from the lamp 6 thereby permanently extinguishing said lamp. WVith another call awaiting at tention, relays 4 and 9 are operated and upon the release of relay 14, the original energizing circuit for test relay 13 is again established and this relay operates to again close the operating circuit for the stepping magnet 15 of switch D and the wipers of said switch are again stepped as before described until said wipers engage the terminals of the calling line, This is true of other switches similar to switch D and as before explained the first switch which reaches the terminals of the calling line has its wipers stopped thereon and a busy condition is placed upon the test terminal of said line by the switch F which stops thereon to cause all other switches to pass over said terminals when the wipers of said switches engage the same.

If the operator after completing the connection for line 1, desires to vacate her position, she depresses the listening-out key 30 instead of the lrey 12. The operation of the key 30 now connects ground through a high resistance 31 to the contact of key 30 and from thence through the left hand normal contact of relay and the innermost left hand contact and left hand winding of relay 14 to grounded battery. The closure of this circuit causes relay 14 to release with the same results as before described. Now,

if there is an unanswered call awaiting attention, the release of relay 14 will cause the switch D to hunt for the terminals of the calling line-by reason of the operation of the test relay 13. but when this line is found by the switch D, although relay will opcrate, the relay 14 will fail to energize through its right hand winding due tothe high resistance 31 thus maintaining the original energizing circuit for the test relay 13 and preventing this relay from releasing with the result that although switch D will stop upon terminals of the calling line, no busy condition will be placed upon the test terminal of this line through the left hand normal contact of relay 13 with the result that some other switch similar to switch D will not be prevented from also engaging and coming to rest upon the terminals of said line. When the operator again assumes her position at the switchboard, the listening-out key is released and upon the lighting of her lamp 11, the operator may again proceed to take care of the calls in a.

lamp and the contact of the supervisory relay 32 of the cord circuit J, in parallel, to grounded battery. The cutoff relay in this manner is prevented from releasing until the termination of the call at which time the operator, upon receivin the proper signal withdraws the plug 28 from jack 29 whereupon the cutoff of relay 3 releases and line 1 is in condition to again initiate a call.

What is claimed is: y I

1. In a signaling system, a line, operators positions, a signal for said line 'at each of said positions, means responsive to a call initiated on said line for connecting said line to one of said positions, and means controlled thereby for flashing oneof said signals in a characteristic manner.

2. In a signaling system, a plurality of subscribers lines, operators positions, a signal for each of said lines at said positions, automatic switches responsive to, calls initiated on said lines for connecting said lines to said'positions, and means operable when one of said switches is connected to a calling line for operating one of said signals in a characteristic manner and for rendering the remaining signals inoperative.

3. In a signaling system, a calling subscribers line, an operators'position, a signal for said line at said position, means operable in response to the initiation of a call on said line to connectto terminals thereof, and means under the control of the operator at said position for causing said signal to flash in a characteristic manner and for connecting said position to said line through the first named means.

4. In a signaling system, a calling sub scr1bersl1ne, operators posltions, a signal for said line at each position, switches operable to hunt for the terminals of said line nor, connecting said position to said line through one or" said switches and rendering inoperative the signals at the other positions.

5. in a signaling system, groups of subscribers lines, an operators position at which said groups of lines terminate, a signal at said position for each line of one of said groups, a key at said position common to said groups of lines, an automatic switch a said position for each group of lines operable to c nncct said position to any calling line in said group under the control of said key, and means operable to actuate the signal tor said calling line in a characteristic manner when the switch associated with said one group or lines connects said operators position to the calling line in said group.

in a signaling system, roups of subs lines, a plurality of operators poions, a switch at each opcrators position for each group of lines, means controlled by the init ation of a call in one of said groups for operating the switches associated with group at the various positions to hunt the calling line, means for stopping one or said itchcs on terminals of the calling line. operator controlled means for preventing other switches from stopping upon said terminals of the calling line and for connecting said calling line through said switch to the ope 'ators position at which said switch appears.

7. In a signaling system, groups of subscribers lines, a plurality of operators positions, a switch at each operators position for each group of lines, means controlled by the initiation of a call in one of said groups for operating the switches associated with said group at the various positions to hunt for the calling line, a signal for said calling line, means for stopping one of said switches on terminals of the calling line, and means thereuponoperable to actuate said signal in a characteristic manner and to connect said calling line through said switch to the operators position at which said switch appears.

8. In a signaling system, groups of subscribers lines, a plurality of operators positions, a switch at each operators position for each group of lines, means controlled by the initiation of a call on a line in one of said groups for operating the switches associated with said group at the various operators positions, a signal for said calling line means for stopping one of said switches on tern'iinals of the calling line, means for preventing other switches from stopping upon said terminals, and means for actuating id signal in a characteristic manner when slid switch stops upon the terminals of the calling line and for connecting said calling line through said switch to the operators position at which said switch appears.

9. In a telephone exchange system, a plurality ot' subscribers lines, a plurality of operators positions, a switch at each of said positions, means controlled by the initiation or a call on one of said lines for operating said switches to hunt for the calling line; means tor stopping one of said switches on tei lnals or" the calling line, manually controlled means for thereupon connecting said calling line to the operators position at which said one of the switches appears, and operator controlled means for permitting one other switch to stop on terminals of said calling line. I

10. in a telephone exchange system, a plurality of subscribers lines, a plurality of operators positions, a switch at each of said positions, means controlled by the initiation of a call on one of said lines for operating said switches to hunt for the calling line, operator controlled means for stopping one of said switches on the terminals of the calling line and for connecting the call ng line to the position at which said one switch appears, means controlled thereby for preventing other switches from stopping on terminals of the calling line, and operator controlled means for rendering said preventing means ineffective, whereby a plu- V rality of switches stop on the terminals of the calling line.

In testimony whereof I have signed my name to this specification this 4th day of December, 1922.

DAWSON M. TAGGART. 

